Flip-flops are often used as the basic storage element in circuit design. When a circuit is not in an active mode it is desirable to reduce the power provided to the circuit while maintaining the state of the circuit. The circuit may be placed in a reduced power mode (e.g., sleep, drowsy) where the power to a portion of the circuit may be turned off. However, the circuitry (e.g., flip-flops) that maintains the state of the circuit may receive power during the reduced power state. The circuitry that maintains the state may need to be low leakage circuitry (e.g., thick gates, long channels, high threshold voltage, reverse bias) since the state may be maintained therein for a period of time.
When the circuit enters a low power mode the clock signal may be deactivated and the circuit may transfer the state to low leakage latches (e.g., balloon latch). The state may be transferred from the active latches to the low leakage latches by pulsing a signal (e.g., low power, low leakage, sleep) to the low leakage latches. After the state is transferred the power provided to the circuit may be turned off with the exception of the power provided to the low leakage latch. When the circuit is ready to become active, the state needs to be restored to the circuit. After the power supply is restored to the circuit, a signal (e.g., restore, active) may be asserted to enable transfer circuitry to transfer the state back to the active latches.